In one form of movable joint, the joint members may have movement toward and from each other. One example of such a joint is that of a track linkage such as used in a track-type vehicle. In such joints, it is desirable to provide means for sealing the joint to maintain lubricant therein. One improved example of such a sealed joint is that disclosed in U.S. Pat. No. 3,841,718 of Harold L. Reinsma, which patent is owned by the assignee hereof. The seal disclosed therein comprises a crescent-shaped ring partially encompassing a load ring. The load ring applies a sealing force to the sealing lip of the seal ring and is preferably made of elastomeric material having effective spring characteristics over a wide operating temperature range. The seal ring includes a thin wall section connecting the driving flange and sealing flange thereof to provide a flexible hinge connection therebetween. The load ring is axially compressed between the driving flange and the sealing flange and, as a result of the flexibility of the hinge portion, develops suitable force for maintaining the sealing flange in sealing engagement with one of the joint members.
Another track pin seal is illustrated in U.S. Pat. No. 3,614,113 of Duane L. Burk, which patent is also owned by the assignee hereof. As disclosed therein, the seal includes a resilient boot encompassing the outer diameter of a pair of frustoconical springs positioned back-to-back and biasing the ends of the boot into sealing engagement with the respective joint members.